“When I heard about this, like on Christmas morning when I heard about the almost attack then, it just brings back all the memories of September 11,” Giuliani said during an interview with CNN’s Larry King.

Giuliani then said he’s concerned that “as we get further away from it, we kind of think it’s, you know, part of our past. And it isn't yet. I mean it will be someday. Someday, it will be just part of our history, like Pearl Harbor is part of our history.”

Suspected terrorist Faisal Shahzad has admitted to authorities that he tried to set off a car bomb in Times Square over the weekend. He was arrested Tuesday night on a plane set to take off for Dubai.

The former Republican mayor warned that Shahzad’s attempted attack as well as a failed attempt to blow up a plane as it landed in Detroit on Christmas Day could be a sign of things to come.

“This is an ongoing menace that we continue to face,” he said. “And these were two real wakeup calls for us, I think, Christmas morning and this one, because, you know, but for the grace of God or good luck, we'd have had a lot of people killed on both occasions.”

“This is an ongoing menace that we continue to face,” Giuliani added. “And these were two real wakeup calls for us, I think, Christmas morning and this one, because, you know, but for the grace of God or good luck, we'd have had a lot of people killed on both occasions.”